Ski resorts near Lake Tahoe apparently owe Africa a big thank you for the nearly 30 feet of snowfall they've enjoyed this season.

The National Oceanic and Atmospheric Administration and the University of California, San Diego collaborated on a three-year study of the connection between aerosols and precipitation in the Sierra Nevada Mountains. A team of researchers was able to directly link Asian and African aerosols -- which can include dust, bacteria, sea salt and smoke -- to U.S. weather patterns. They determined that dust and other microorganisms from as far away as the Sahara desert contribute largely to the rain and snow on which California relies for its water supply.

Jessie Creamean, a postdoctoral associate at NOAA's Boulder research laboratory, co-authored the study with Kaitlyn Suski, a UCSD graduate student in the school's atmospheric chemistry department.

"A lot of people don't understand that aerosols play a role in cloud formation, and the enhancement or suppression of rain and snow," Creamean said. "If you look at a cloud, those cloud particles are likely formed by little aerosols ... That's important to the water cycle, particularly in California, where the region depends on winter storms for water."

This study is not the first to examine the transport of dust from Africa to the West Coast of the U.S., but most have focused on the travel of dust across the Atlantic Ocean, whereas Creamean's team was concerned with dust carried across the Pacific.

"It starts in the major deserts -- the Sahara and the Asian deserts -- and basically it's lofted really high into the atmosphere by strong winds," Creamean said. "It can be carried really long distances, and actually make it over to California in five to 10 days."

Colorado also depends on aerosols for its precipitation, but with a much shorter timescale and distance. The majority of snowfall in the Rocky Mountains can be traced to dust from the Colorado Plateau, which only has to travel a matter of hours.

"As a result, the dust materials we're collecting out of the snowpack are comparatively quite large," said Chris Landry, executive director at the Center for Snow and Avalanche Studies. "The winds that are delivering that dust have enough energy to elevate and carry this large material, whereas the dust that (Creamean's) team collected was much smaller."

Landry said he hoped a team as focused as Creamean's would soon conduct a similar study in Colorado.

"There's a lot of implications of their project," he said, "But I think their own conclusion was that the effects of dust in further interior ranges of the U.S. are still to be determined ... These are unexpected results, so if it's true in Colorado, it would be important to understand."